In the eastern United States, a "fritter" is any bite-size piece of food that has been breaded and deep fried in oil. "Grouper Fritters" are bite-sized pieces of grouper fish; coated in bread crumbs or flour, then deep fried in oil. "Fritters" are usually served with various dipping sauces. Conch fritters are especially popular in the mid-atlantic and southeastern states.

The food "fritter" is different in the UK, USA, and Asia. Because the context in question is fish ("grouper"), it would be UK fritters.

A fritter is food fried in batter (mixture of egg and milk). A grouper is a kind of fish. So a grouper fritter is that kind of fish fried in batter.